This invention relates generally to sheet material forming devices and more specifically to a portable sheet material forming tool incorporating a unique force generating mechanism.
In the manufacture of products there is often the need to join several pieces of sheet material to build various assemblies and subassemblies. In this regard, there are many different means for accomplishing this joining task. For example, there is adhesive bonding, welding or cold deformation. In cold deformation, several pieces of sheet material are plastically deformed in such a manner that they are locked together. Depending on the thickness, strength, and/or the number of pieces of material to be joined, a great amount of force is required to accomplish this plastic deformation.
An apparatus and method for accomplishing cold forming joining of sheet material is disclosed in commonly assigned U.S. Pat. Nos. 5,027,503, 4,910,853, 4,757,609, the disclosures of which are hereby expressly incorporated herein by reference. As is disclosed in these patents, the sheets of material to be joined are placed between complementary die members. A suitable press is then activated to provide the force and displacement necessary to deform the material between the die members thereby joining the sheets of material together. This process has a number of advantages over such joining processes as resistance/spot welding and bonding which are more fully discussed in the above referenced patents.
In the embodiments disclosed in the above U.S. patents, the dies are generally attached to relatively large presses thus requiring the sheets to be joined to be manipulated with respect to the press. In contrast, portable spot welding devices have been in existence for many years. These smaller devices allow for the joining tool to be manipulated with respect to the workpiece thereby making it easier to work with large workpieces. Smaller portable tools are available which can provide the necessary clamping force to join the sheets and which allow for manipulation of the joining tool with respect to the workpiece and thus allow for easier operations with larger workpieces. One such tool is disclosed in commonly assigned U.S. Pat. No. 4,878,284, the disclosure of which is hereby expressly incorporated by reference herein. These tools generally incorporate a pneumatic or hydraulic cylinder to provide the force and displacement necessary for sheet material joining and clamping. Unfortunately, the levels of force generated by these devices is limited by the size of the cylinder which can be incorporated into the tool while still maintaining the compact, light weight nature of a hand held portable tool.
Accordingly, the present invention is uniquely adapted to provide the force necessary for sheet material joining in a compact, lightweight tool. In the present invention, a force generating member, a resilient ram, is disposed within an actuation chamber where either pneumatic or hydraulic fluid pressure is allowed to bear against the relatively large ram surface causing a deflection of the ram in a first direction and translation of an end of the ram in a second direction substantially perpendicular to the first direction. A working force, larger than the force of the fluid bearing on the ram surface, is thereby generated along this direction of translation.
Another advantage of the present invention is that it provides for generating large amounts of working or clamping force within a relatively small, light weight tool.
Still another advantage of the present invention is that it is readily adaptable to a number of different applications including sheet material joining, clamping, or resistance/spot welding or any other force-requiring applications.
Additional advantages and features of the present invention will become apparent from the subsequent description and the subjoined claims taken in conjunction with the accompanying drawings.